Insulating bushing



July l, 1930. G. A. BURNHAM 1,769,175

` INSULATING UsHING Filed June 30, 1926 Ill! IHHHHHIHI 1"! nllllllielml |lll'l I lIlll I llll' Patented July l, 1930 UNITED STATES PATENT OFFICE GEORGE A. BURNHAM, OF SAUGUS, MASSACHUSETTS, ASSIGNOR TO CONDIT ELECTRICAL nanou oF MASSACHUSETTS y ACTURING CORPORATION, OF SOUTH BOSTON, MASSACHUSETTS, A CORPO- INSULATING BUSHING Application led June 30,

This invention relates to oil filled insulating bushings for high tension electric circuit leads and has for an object the provision of an oil filled bushing that can be opened read- 5 ily for inspection and replacement of parts and has a minimum of joints that must be maintained oil tight.

A further object is generally to improve the construction of electric bushings.

Fig. 1 is a side elevation of an insulating bushing embodying the invention.

Fig. 2 is a sectional elevation of the insulator of Fig. 1.

The insulating bushing embodying this invention is adapted to be fixed in the casing wall 10 of any suitable electric apparatus to insulate the high tension conductor 12 therefrom. The insulator comprises an approximately vertically disposed lower hollow insulating member or shell 14 which is composed of any-.suitable insulating material, as porcelain. Said insulating member is open at thetop andV is tapered downwardly toward the. lower end. Said high tension conductor 12l is extended into said insulating member and through the bottom thereof and is fixed removably in the bottom wall of said insulatin member in an oil tight manner by any sultable means whereby to seal the bottom of the insulating member. The lower end of said conductor may be provided with suitable means as the nuts 16 for connection with the electric a paratus contained ,Within the casing 10. aid insulating member 14 is comosed of one piece of insulating material and 1s received within the opening 18 in the casing wall so that its upper end is disposed a substa-ntial distance above said wall. The insulator is fixed removably to said wall in the aforesaid relation by a clamping rin 20 which encircles said insulating member a out in the middle thereof and is fixed .rigidly thereto by cement 22. Said insulating member is adapted to contain oil or other insulating medium to some, level a/-a which is below the open top of the insulator and is substantially'above the zone of the casing 10 and the clamping ring 20, the insulating? liquid thus occupying the region of greatest electric stress and thus adequately insulating the con- 1926. Serial No. 119,708.

ductor 12 from the grounded casing. Suitably spaced and concentric insulating tubes 24 may be disposed about said conductor 12 to provide further insulation thereof and said tubes are extended above the oil level to increase the resistance of the insulator to flashovcr above the surface of the oil.

The lower insulating member 14 is covered and partially'enclosed by the upper insulat-v ing member or shell 26 which is hollow to receive within it the upper portion of said lowerl insulating member and the insulating tubes 24. The conductor 12 is extended loosely through the upper end of said 'insulator 26 and is provided with suitable means asnuts 28 for-connection with a circuit lead. The lower open end of said insulator 26surrounds the lower insulating member and its clamping ring and is secured removably to the casing wall 10 by a clamping ring 30 which is rig- 4idly fixed by 'cement to the lower end of said insulator. A water tight packing 32 may be interposed between said clamping ring 30 and the casing Wall whereby to prevent moisture from entering the interior of the insulator. The upper insulator-section is provided with the usual petticoats or capes 34.

As thus arranged the insulator may be readily opened for inspection by the removal of the section 26 and the bolts 36 which se-4 cure said section detachably to the base'10.

v The only joint that need be maintained oil tight is the joint at the bottom of the insulator 14 through which the conductor 12 is ex tended and since this joint has small area, it

can be made and maintained oil tight with no difliculty. f

The particular relation existing between the conducting stud and the insulating shell form no part of the presentinvention, but.,

fixed thereto, an upper inverted hollow oilfree insulating shell which is open at the bottom only, and is disposed about and in surrounding and enclosing relation and extends and is spaced above the upper end of said lower insulating shell for a substantial distance, an axial conduct-ing stud extended through said upper and lower shells and immersed in the oil in said lower shell, means cooperating with said stud forming an oiltight closure at the bottom end of said lower shell, anv attaching collar surrounding and xed to the bottom of said upper shell, and means connected with said collars supporting said shells in the aforesaid relation permitting the removal of said upper shell independently of said lower shell.

2. An insulating bushing including the combination ofalower hollow insulating shell containing oil and which is open at the top, an upper hollow oil-free insulating shell supported independently of said lower shell and which is open at the bottom, and is disposed about and in surrounding and enclosing relation and extends and is spaced above the upshells in the aforesaid relation independent.

ly of each other, said means also including y means to provide a fluid-tight connection between said shells.

3. The combination with a casing wall having an aperture therein, of a vertically-disposed insulating shell having an open top extended through said aperture and disposed therein with its open top located substantially above the top of said casing wall, an upper open bottom insulating shell which is disposed about and extends and is spaced above the upper end of said lower shell for a substantial distance, an electric conductor extended through said upper and lower insulating shells and having a Huid tight connection with said lower shell at the bottom thereof, said lower shell adapted to contain an insulating fluid in which said conductor is immersed to a level substantially above said casing wall and independent means securing said upper and lower shells to said casing wall in the aforesaid relation.

4;. The combination with a easing wall having an aperture therein, of a vertically disposed insulating shell having an open top extended through said aperture and disposed therein with its open top located substantially above the top of said casing wall, an electrie conductor extended through said insulating shell and having a fluid tight connection with the bottom thereof, said shell containing an insulating liquid to a. level substantially above said casing wall, in which liquid said conductor is immersed and an insulating cover for the open to of said shell having an independent detae iable connection with said casing wall.

5. The combination with a casing wall having an aperture therein, of a lower vertically-disposed insulating shell disposed. within said aperture and having its open top disposed substantially above said easing wall, an attaching ring rigidly afiixed to said insulating shell substantially below the o en top thereof, means securing said attaching ring detachably with said casing wall, a cover for the open top of said insulating shell including an upper insulating shell substantially closed at the top and open at the bottom and disposed above and about and extended a subtantial distance below the upper open end of said lower insulating shell, an attaching ring aflixed to the lower end of said second shell, means detachably securing said attaching ring to the casing wall` said lower insulating shell adapted to contain oil to a level below the open top thereof and above the top of its attaching ring, said upper shell adapted to be without oil, and a conductor passed axially through said shells and immersed in the oil in said lower shell and having a fluid tight connection with the bottom thereof.

(i An oil-containing insulating bushing consisting of a lower insulating shell containing oil and which is open at the top and has an openin T through its bottom, a conductor extended axially in said shell through the open top and into the bottom opening and having an oil-tight seal at said bottom opening, a metal attaehin member encircling and secured to said she l intermediate its ends and substantially below the open top, said shell adapted to contain oil to a level substantially abovethe top of said attaching member, in which oil said conductor is immersed, an oil free upper insulating shell which is open at the bottom and his an opening in its top in which said conductor is received disposed over the open top of said lower oil-containing shell and surrounding and depending over the side wall of said shell and having its open bottom terminated substantially below the open top of said lower shell, and means detachably joining the bottom of said upper shell and said attaching member, said means constituting a support for said outer shell. y

In testimony whereof, I have signed my name to this specification;

GEORGE A. BURNHAM. 

